Simultaneous Recovery of Monomers and Oligomers

Introduction

The waste obtained at the bottom of the distillation tower used in caprolactum recovery contains trapped caprolactum along with oligomers. After segregating the capralactum rich waste and oligomer rich waste, the caprolactum rich waste, which is soluble in water at room temperature, is subjected to chemical purification and distillation for recovery of caprolactum. The oligomer rich waste containing both cyclic and linear oligomers was found to be polymerisable to moderate molecular weights under controlled reaction conditions. This material is subjected to either homo and/or co-polymerisation to produce different types of adhesives and coatings.

A specific quantity of Oligomer waste consisting of cyclic and linear oligomer is taken in a reactor to which a specified amount of water is added and heated in a heating bath. Inert gas, preferably Nitrogen is flushed into the reactor and the temperature of the reaction is raised. After maintaining the temperature for the desired period a weighed amount of Manomer I is added. The reactor is heated up again to raise the temperature to the desired level and maintained for about 30 minutes. Subsequently a weighed amount of Manomer II is added and the reactor is heated further for attaining another desired level of temperature. The temperature is maintained at this level for a specific duration with or without vacuum so that the required copolymer, Nylon 6 : Polyester or Nylon 6 & 66 is produced. In the case of Homopolymerisation, nitrogen is flushed through the empty reactor first followed by the addition of oligomeric waste. The reactor is then fixed with a stirrer and placed on a heating arrangement. Subsequently, the reactor is charged with Oligomeric waste and heated with continuous stirring. On attaining the desired temperature in about 30 minutes and allowed to remain at this temperature for a specific duration, homopolymer of desired molecular weight is produced. The polymers as obtained by the process described above have been tested for end use application, particularly as hot metal adhesive by known methods. The lap-shear and T-peel tests carried out have demonstrated better adhesive strength which may be attributed to the random structure of the prepared polymers.

Special Features: Conversion of oligomeric waste or polymeric waste into a useful hot metal adhesive , Additional step involving addition flow agents and/or plasticisers as practiced in the conventional method is eliminated. Reduction in production cost. Can be used for treating oligomer or polymer waste from both caprolactum recovery plant as well as nylon 6 processing units.

Prospective Users: The method is useful for (i) Caprolactum processing units for producing a valuable by-product (ii) small/medium chemical industries for conversion of nylon polymeric and oligomeric waste material to a useful product.

Type of Technology: Process

Status of IPR Protection: Indian Patent Application no: 749/DEL/99 dated 18th May 1999 with the title "A Method for Co-polymerisation & Homo-polymerisation of Oligomeric Wastes obtained from Nylon - 6 production, and products thereof "

Status of Development: Investigations have been carried out in collaboration with Caprolactum processing industry. Process has been developed for producing hot metal adhesive The end product, viz., the hot metal adhesive ha

Requirement of Raw Materials/Components:

Oligomeric Waste
Acetic acid

Major Equipment & Facilities required: Stainless Steel batch reactor having a capacity of 800 kgs. with heating capacity upto 300 deg.

Glossary: ASTM American Standard Testing Methods; kwh Kilo Watt Hours; kgs. Kilo grams; Rs. rupees

Developed by : Prof. K A Agarwal
Department: Textile Technology

Contact:

Managing Director
Foundation for Innovation and Technology Transfer (FITT)
Indian Institute of Technology, Delhi
Hauz Khas, New Delhi-110016, INDIA
Tel : 91-011-26597167, 26857762, 26581013, 26597153
Fax : 91-011-26851169
E-mail : drkdpn@gmail.com